The present invention relates to light fixture cooling features, and particularly, to providing a light fixture with internal and external surfaces and cooling paths to facilitate cooling.
Managing the temperature of light sources in a light fixture is generally important to performance and longevity. This is particularly true with newer highly efficient lighting technology, for example, light sources such as LEDs or laser diodes. LEDs are generally selected to maximize the light output for a given power consumption at a reasonable cost. Because LED light sources operate at a much lower temperature than typical incandescent light sources, less energy is wasted in the form of heat production. However, LEDs tend to be more sensitive to operating temperature and lower operating temperatures also provide a much smaller temperature difference between the LED and the ambient environment, thus requiring greater attention to thermal management to transfer and dissipate any excess heat generated by the LED driver and emitter so that the design operating temperature for the components are not exceeded.
As temperatures rise, the efficacy of the LED is reduced, reducing the light output, and reducing the lifespan of the LED. LED lighting fixtures generally include both LED drivers and LED emitters. To facilitate dissipation of heat, convection, conduction, and radiation are available modes of heat transfer. For LED light fixtures, dissipation of heat by conduction is often provided by one or more LED packages being mounted on a heat sink The heatsink is generally integral with or thermally coupled with the light housing, which often includes external cooling fins to further facilitate the dissipation of heat from the light fixture by convection and radiation.
For example, one prior art design seeking to address these concerns provides fins between a central light housing and an outer rim that are thin in width and height, and thus provide vary little surface area to transfer heat from the light to the channel of air passing through the light fixture. Additionally, no structure limits visibility vertically through the cooling channels or redirects airflow horizontally across further surfaces of such a light fixture mounted to a ceiling or similar overhanging structure.
Another prior art design seeking to address these concerns provides a very narrow set of vertical airflow channels around the periphery of the central light housing, the channels formed by an outer ring and vertical cooling fins, and the vertical cooling fins extend radially inwardly above and toward the center of the central light housing. Thus, in the case of mounting the light fixture against a ceiling, any airflow extending upwardly through the very narrow airflow channels flows outwardly between the ceiling and top of the light fixture, and thus will not benefit provide from further heat exchange if the air flow had included flow across the radially inwardly extending fins on the top side of the central light housing.
Therefore, it is desirable to provide a lighting fixture design that maximizes cooling by thermal convection for the light emitter and driver in a central light package housing, shields the cooling features and through the fixture view from as many viewing angles as practical, and redirects vertical airflow to a radially outwardly direction and across further cooling structure when mounted against a ceiling.